Today, Speaker of the House Nancy Pelosi (D-Ca.) announced that the House is launching a formal impeachment inquiry into President Donald Trump. Pelosi's announcement came after Representative John Lewis (D-Ga.) and former Vice President Joe Biden called for impeachment proceedings to begin if the president chooses not to comply with Congress. Lewis, a civil-rights icon and major figure in the Congressional Black Caucus, has a lot of pull in the House, and his announcement served as a signal to other high-profile members of the House, including Pelosi, that the time for impeachment is now.

According to Axios (at time of posting), "154 members of the caucus support impeachment, and that number is rapidly growing." Other members who have commented on impeachment recently include Rep. Rose DeLauro (D-CT), Rep. Debbie Dingell (D-MI), and seven freshmen members who published an op-ed in the Washington Post.

WATCH: Pelosi announces formal impeachment inquiry against President TrumpYouTube

So, why is impeachment gaining ground now?

Word spread late last week that a whistleblower report alleging wrongdoing by President Trump was found credible by the inspector general of the Intelligence Community. The ICIG had been attempting to share this information with Congress, but as an employee of the executive branch, he was blocked by the White House from doing so. The explicit details of the report remained mostly unclear, except that Trump's misconduct had to do with his communication with a foreign leader. This foreign leader was then identified as Ukranian President, Volodymyr Zelensky.

Trump allegedly asked Zelensky to provide dirt on former Vice President Joe Biden.

In a phone conversation with Zelensky, Trump allegedly asked him eight times to investigate the role that Joe Biden played in the firing of a Ukranian prosecutor who was opening an inquiry into an energy company that Biden's son, Hunter, served on the board of. The Trump administration has been pushing for an investigation into Biden and his son's conduct, although it has been found that Biden was simply echoing the position of the broader U.S. government, not acting only in his son's interest. Trump called Zelensky on July 25. This date is significant because just days before, Trump decided to withhold $400 million of foreign aid from Ukraine. Essentially, Trump was asking for dirt on his biggest political opponent while holding major funding for Ukraine's military hostage.

Democrats are searching for answers, and they want them ASAP.

The acting director of National Intelligence, Joseph Maguire, is set to testify before the House Intelligence Committee this Thursday. The committee is expecting to receive the full whistleblower complaint before that testimony as it will be the focus of the session. A non-binding resolution that formally calls for the immediate release of the complaint to Congress unanimously passed in the Senate earlier today. The counsel for the whistleblower has publicly stated that he or she would like to testify before Congress. As the investigation already seems to be progressing rapidly, Trump has agreed to supply a transcript of the call between him and President Zelensky that is being brought into question.

This is the logical next step for House Democrats.

Various committees have been conducting investigations into Trump on an array of different issues, yet they have declined to officially begin an impeachment inquiry. The questions surrounding Ukraine will no doubt prompt another investigation to join the litany of ones being conducted by Congress already. However, a formal impeachment inquiry puts Congress in a better legal position to conduct oversight work. It could also mean that Democrats initiate a formal vote to approve articles of impeachment for the President at the conclusion of the inquiry.

Using the power of the presidency to threaten foreign leaders in order to collect dirt on a political opponent is an impeachable offense.